The alkoxylcarbonylation of halogenated aromatic, vinyl or heterocyclic compounds is known in the art U.S. Pat. No. 3,988,358, for example, describes the alkoxylcarbonylation of such compounds at a temperature of approximately 20.degree.-150.degree. C. and at approximately 1 to 100 atmospheres in the presence of a palladium-based catalyst of the formula PdX.sub.2 [P(C.sub.6 H.sub.5).sub.3 ].sub.1 or .sub.2 in which X is a halogen or the acetate group and in the presence of an amine.
In the disclosure of said patent it is stated that tri-phenylphosphine can be replaced by trianisylphosphine, tri-p-tolylphosphine, tri-n-butylphosphine, triethylphosphine and the like. All the tests were carried out on triphenyl-phosphine, which is at the present time the most widely employed phosphine for this type of reaction. The disadvantage of this phosphine is that it allows only the alkoxycarbonylation of aromatic bromo or iodo compounds and never the alkoxycarbonylation of chloro compounds. At present, chlorinated aromatic compounds are much less costly than brominated compounds; it is therefore an object of the present invention to describe an alkoxycarbonylation process using aromatic chloro compounds as a starting material.